KR20130051130A - Backlight unit and display apparatus having the same - Google Patents

Abstract

PURPOSE: A backlight unit and a display apparatus having the same are provided to emit the light of a light source to the back surface of a display panel by forming a first and a second pattern part in a light guide plate. CONSTITUTION: The first pattern part(210) of a light guide plate(200) is formed on the lower surface(201) of the light guide plate. The first pattern part includes first pattern lines vertically extended in the direction of the light of a light source, and totally reflects the light to the upper surface(202) of the light guide plate. A second pattern part(220) of the light guide plate is formed on the upper surface. The second pattern part includes second pattern lines extended in parallel in the direction of the light, and emits the light guided by the light guide plate to the second pattern line.

Description

Backlight unit and display device having same {BACKLIGHT UNIT AND DISPLAY APPARATUS HAVING THE SAME}

The present invention relates to a backlight unit for generating light to display an image on a display panel and providing the same to a display panel, and a display apparatus having the same. Specifically, the efficiency of light supplied to a display panel is improved. It relates to a backlight unit and a display device having the same.

The display apparatus includes a display panel for displaying an image and can display broadcast signals or image signals / image data of various formats. The display apparatus is implemented as a TV or a monitor. The display panel is implemented in various configuration types such as a liquid crystal panel and a plasma panel according to its characteristics and applied to various display devices. Here, when a liquid crystal panel that cannot generate light by itself is applied to a display panel, the display device includes a backlight unit for generating light and supplying the light to the display panel.

The backlight unit of such a display device is a light source for forming light, and employs a light emitting diode device having excellent characteristics in terms of environmental pollution, response speed, etc., compared to a cold cathode fluorescent lamp generally adopted in the past. In addition, the backlight unit may be classified into a direct type and an edge type according to a relative arrangement position of the light source with respect to the light guide plate.

In the direct type backlight unit, light sources are disposed in parallel along the rear surface of the light guide plate, so that each light source directly projects light toward the front display panel. In contrast, in the edge type backlight unit, the light source is disposed in a bar shape along the edge of the light guide plate, and the light from the light source is incident on the side of the light guide plate and is projected onto the display panel.

A backlight unit of a display device according to an embodiment of the present invention, the light source unit disposed in at least one of the corner region of the display panel; A light guide plate disposed behind the display panel and emitting light emitted from the light source to a rear surface of the display panel, wherein the light guide plate extends orthogonally to the direction of the irradiation light on a lower plate surface of the light guide plate; A first pattern portion having a first pattern line, the first pattern portion totally reflecting the irradiation light onto an upper surface of the light guide plate; A plurality of second pattern lines extending in parallel to the direction of the irradiation light on the upper surface of the light guide plate, wherein the light propagating in the light guide plate is guided so that the light propagates and exits along the second pattern lines; It characterized in that it comprises two pattern portion.

Here, the first pattern line may be engraved on the lower plate surface of the light guide plate to have a wedge or prism-shaped cross section.

Here, in an end surface of the first pattern line, an angle of a vertex toward the upper plate surface of the light guide plate may be 70 degrees or more and 110 degrees or less.

In addition, a pitch distance between two adjacent first pattern lines may be less than 0.5 millimeter.

In addition, the circumferential angle of the light reflected by the first pattern line and emitted from the light guide plate may be in a range of -10 degrees to 10 degrees with respect to a normal axis with respect to the rear surface of the display panel.

The distribution of the plurality of first pattern lines on the lower plate surface of the light guide plate may be denser as the distance from the light source portion increases.

In addition, the second pattern line may have a lenticular shape embossed on the top surface of the light guide plate.

Here, the width of one second pattern line may be 100 micrometers or less, and the ratio of height to width of one second pattern line may be 0.35 or more.

The light source unit may include a plurality of light emitting elements sequentially arranged, and the plurality of second pattern lines may be disposed to correspond to the plurality of light emitting elements, and any one of the second pattern lines may be configured to emit the plurality of light emitting elements. The emission of light irradiated from any of the corresponding positions among the elements can be guided.

Here, each of the second pattern lines may block the inflow of light irradiated from the rest of the plurality of light emitting devices except for any one of the corresponding positions to a predetermined level or less.

The display device may further include a diffusion sheet interposed between the display panel and the upper surface of the light guide plate and scattering light emitted from the upper surface.

In addition, the display device according to an embodiment of the present invention is characterized by including a display panel and a backlight unit having the above-described structure for supplying light to the display panel.

1 is an exploded perspective view of a display device according to an embodiment of the present invention,
2 is a perspective view illustrating main parts of the light guide plate in the display device of FIG. 1;
3 is a side cross-sectional view of a main portion illustrating a reflection form of light by the first pattern unit in the display device of FIG. 1;
4A to 4D are graphs illustrating an emission angle distribution of light detected on an entire surface of a display panel in a display device of a comparison target structure compared to the display device of FIG. 1;
5A and 5B are graphs illustrating an emission angle distribution of light detected on an entire surface of a display panel in the display device of FIG. 1;
6 is a side cross-sectional view showing main parts of the second pattern unit in the display device of FIG. 1;
FIG. 7 is a plan view of a main portion showing a traveling pattern of light by a second pattern unit in the display device of FIG. 1; FIG.
8 is a plan view illustrating a guide efficiency experiment method of light by a second pattern unit in the display device of FIG. 1;
9 is a graph comparing a guide efficiency result according to the experiment of FIG. 8 with a comparison target configuration;
FIG. 10 is a block diagram illustrating the configuration of the display device of FIG. 1.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. In the following embodiments, only configurations directly related to the concept of the present invention will be described, and description of other configurations will be omitted. However, it is to be understood that, in the implementation of the apparatus or system to which the spirit of the present invention is applied, it is not meant that the configuration omitted from the description is unnecessary.

1 is a schematic exploded perspective view of a display apparatus 1 according to an embodiment of the present invention.

As shown in FIG. 1, the display device 1 according to the present exemplary embodiment includes a cover part 10 and 20 forming an accommodating space therein and an accommodation space accommodated by the cover part 10 and 20, and the image is displayed. The display panel 30 displayed on the plate surface and the backlight housed in the receiving space by the cover parts 10 and 20 and generating and supplying light to the display panel 30 so that an image is displayed on the display panel 30. Unit 40.

First, each direction shown in FIG. 1 is demonstrated. The X, Y, and Z directions are basically the horizontal, vertical, and height directions of the display panel 30 in Fig. The display panel 30 is disposed on the X-Y plane, and the cover parts 10 and 20, the display panel 30, and the backlight unit 40 are disposed to be stacked along the Z direction axis. Hereinafter, each drawing and embodiment including FIG. 1 will be described based on this direction definition. Here, the directions opposite to the X, Y, and Z directions are represented by -X, -Y, and -Z directions, respectively, and the X-Y plane means a plane formed by an axis in the X direction and an axis in the Y direction.

The cover parts 10 and 20 form an external shape of the display device 1 and support the display panel 30 and the backlight unit 40 accommodated therein. In the drawing, when the Z direction is front / front and the −Z direction is rear / rear with respect to the display panel 30, the cover parts 10 and 20 support the front cover 10 supporting the front of the display panel 30. And a rear cover 20 supporting the rear of the backlight unit 40.

The front cover 10 and the rear cover 20 together form an accommodation space and support the edge regions of the display panel 30 and the backlight unit 40. In particular, the front cover 10 has an opening for exposing the image display area of the display panel 30 on a plate surface parallel to the X-Y plane.

The display panel 30 is implemented as a liquid crystal panel according to the present embodiment. The display panel 30 is filled with a liquid crystal layer (not shown) between two substrates (not shown), the image is displayed on the plate surface by adjusting the arrangement of the liquid crystal layer (not shown) in accordance with the application of the drive signal. Can be. The display panel 30 does not emit light independently and receives light from the backlight unit 40 to display an image in the image display area.

The display panel 30 has a driving circuit board (not shown), and when a driving signal is applied from the driving circuit board, the liquid crystal (not shown) of the display panel 30 rotates at a predetermined angle. As a result, light transmission characteristics of each cell (not shown) constituting the image display area of the display panel 30 are different, so that an image may be displayed on the image display area.

The backlight unit 40 is disposed at the back of the display panel 30, that is, in the −Z direction of the display panel 30 to supply light to the display panel 30. The backlight unit 40 includes a light source unit 100 disposed at a corner of the display panel 30, a light guide plate 200 disposed in parallel to the display panel 30 so as to face a rear surface of the display panel 30, and a light guide plate. The reflective plate 300 disposed below the light guide plate 200 facing the lower plate surface of the 200, and the diffusion sheet 400 interposed between the display panel 30 and the light guide plate 200.

The light source unit 100 generates light and irradiates the generated light to the light guide plate 200. The light source unit 100 is erected with respect to the plate surface of the display panel 30, that is, the X-Y plane, and is disposed along at least one of four direction edges of the display panel 30 or the light guide plate 200.

According to the present embodiment, the light source unit 100 is installed along the side wall of the corner of the light guide plate 200 in the -Y direction, but this is merely an example of implementation and does not limit the spirit of the present invention. The light source unit 100 may be installed along any one or two or more of the four direction edges of the light guide plate 200.

The light source unit 100 is sequentially disposed along the X direction and includes a plurality of light emitting devices 110 generating and irradiating light, and a module substrate 120 on which the light emitting devices 110 are flashable.

The light emitting element 110 irradiates light toward a direction parallel to the plate surface of the display panel 30, for example, a -Y direction. The light emitting device 110 is implemented as a light-emitting diode (LED) according to the present embodiment, and receives a driving power and a flashing control signal for blinking from the module substrate 120.

The light emitting device 110 may include a blue LED, a green LED, and a red LED, and the blue light, the green light, and the red light emitted from the LEDs of each color may be mixed with each other to form white light having excellent color reproducibility. However, this is only an example, and the light emitting device 110 may include a white LED that directly generates white light.

The module substrate 120 has a plurality of light emitting elements 110 mounted on a plate surface facing the Y direction. The module substrate 120 has a wiring configuration (not shown) for providing power from the system power supply of the display device 1 to the mounted light emitting device 110, and these wiring configurations provide power to each light emitting device 110. By transmitting, it is possible to implement local dimming to selectively control the blinking of each light emitting device 110.

The light guide plate 200 is a plastic lens made of an acrylic injection product and the like, and uniformly transmits the light incident from the light source unit 100 to the entire image display area of the display panel. In the light guide plate 200, an upper plate surface that is a plate surface in the Z direction faces the display panel 30, and a lower plate surface that is a plate surface in the −Z direction faces the reflective plate 300. In addition, of the four sidewalls in the four directions of the light guide plate 200 formed between the upper plate surface and the lower plate surface, the sidewalls in the −Y direction face the light emitting device 110. Irradiation light from the light emitting element 110 is incident on the side wall in the -Y direction.

The light guide plate 200 according to the present exemplary embodiment includes a first pattern part 210 formed on the lower plate surface and totally reflecting the light propagated from the light source unit 100 and propagating in the light guide plate 200 toward the upper plate surface, and the upper plate. The second pattern part 220 is formed on the surface and guides the light propagated in the light guide plate 200 to be emitted. A detailed description of the first pattern portion 210 and the second pattern portion 220 will be described later.

The reflecting plate 300 reflects the light exiting from the inside of the light guide plate 200 to the outside of the light guide plate 200 to be incident back into the light guide plate 200. To this end, the plate surface of the reflector 300 has a total reflection characteristic.

The diffusion sheet 400 is disposed in parallel between the display panel 30 and the display panel 30 and the light guide plate 200. The diffusion sheet 400 scatters and diffuses the light emitted from the light guide plate 200 to transmit the uniformed light to the display panel 30.

Hereinafter, a detailed configuration of the light guide plate 200 according to the present embodiment will be described with reference to FIG. 2. FIG. 2 is a perspective view illustrating main parts of the light guide plate 200, and the light source unit 100 represents only the light emitting device 110 in order to clearly show the present embodiment.

As shown in FIG. 2, the light guide plate 200 has a rectangular plate shape. The light guide plate 200 has an upper plate surface 202 which is a plate surface in the Z direction facing the display panel 30 or the diffusion sheet 400, and a lower plate surface 201 which is a plate surface in the -Z direction opposite to the upper plate surface 202. And the side wall 203 which is a plate surface in the -Y direction orthogonal to the upper plate surface 202 and the lower plate surface 201.

Light irradiated from the light emitting device 110 is incident on the sidewall 203 and propagates in the light guide plate 200. When the light propagating in the LGP 200 reaches the lower plate 201, the light is reflected by the first pattern part 210 formed on the lower plate 201 and is directed toward the upper plate 202. In addition, the light reaching the upper plate surface 202 is emitted to the diffusion sheet 400 through the second pattern portion 220.

When the light efficiency from the light emitting element 110 reaches the display panel 30 is the best light efficiency, the emission angle of the light emitted from the light guide plate 200 is the normal axis to the plate surface of the display panel 30, That is, the case is parallel to the Z direction axis on the drawing. That is, when the circumferential angle when light is emitted to the light guide plate 200 is 90 degrees with respect to the plate surface of the display panel 30, the maximum light efficiency is obtained.

However, when all the light is incident 90 degrees to the plate surface of the display panel 30, considering the function of the diffusion sheet 400 to scatter and diffuse the light, the display panel 30 may not be advantageous in terms of uniformity of the overall brightness. have. In this regard, the circumferential angle of the light emitted from the light guide plate 200 is set to be within a range of -10 degrees to 10 degrees with respect to the normal axis with respect to the plate surface of the display panel 30.

The first pattern part 210 and the second pattern part 220 are provided to set the main angle of the light, which will be described.

The first pattern portion 210 includes a plurality of first pattern lines 210 extending orthogonally to the traveling direction of the irradiation light from the light emitting element 110 on the lower plate surface 201. That is, while the traveling direction of the irradiation light is Y in the drawing, each of the first pattern lines 210 extends in the X direction, and the plurality of first pattern lines 210 are sequentially disposed along the Y direction.

The cross section of the first pattern line 210 has a wedge or prism shape. The cross section herein refers to a cross section cut along the radial direction of the first pattern line 210 along a radial direction, that is, a cross section cut parallel to the Y-Z plane.

In this embodiment, the cross-section of the first pattern line 210 is an isosceles triangle, but three corner lengths may be different.

The first pattern line 210 is engraved on the lower plate surface 201 such that a vertex of a wedge shape having a cross section faces the display panel 30. Here, the first pattern line 210 is provided so that the light propagated in the light guide plate 200 is totally reflected, and a separate mirror surface treatment may be performed for this purpose.

The first pattern line 210 that totally reflects light may be implemented by various methods, and does not limit the spirit of the present invention. For example, in the process of manufacturing the light guide plate 200 by an injection process, the first pattern line 210 may be formed through a shape design of a mold or the like.

For comparison with the present embodiment, in the case of a light guide plate of a conventional backlight unit, a light reflection pattern is formed on the light guide plate by forming a pattern by burning the lower plate surface of the light guide plate with a laser or by printing a pattern on the lower plate surface of the light guide plate. However, such a conventional light reflection pattern, because of its manufacturing characteristics, the pattern includes scratches, so that the pattern scatters light.

Therefore, the first pattern line 210 according to the present embodiment can improve the light efficiency compared to the conventional pattern described above.

Hereinafter, the detailed configuration of the first pattern portion 210 will be described with reference to FIG. 3. 3 is a main sectional side view showing the reflection form of light by the first pattern portion 210.

As illustrated in FIG. 3, light emitted from the light emitting element 110 is incident on the sidewall 203 of the light guide plate 200 (L1). The irradiation light L1 propagates in the Y direction along the inside of the light guide plate 200 and is reflected by the plurality of first pattern lines 210 formed on the lower plate surface 201 to the upper plate surface 202 (L2).

In the cross section of the first pattern line 210, the angle D1 of the vertex toward the upper plate surface 202 is set to 70 degrees or more and 110 degrees or less, and accordingly, the base side angle D2 of the cross section is set to 35 degrees or more and 80 degrees or less. . Thereby, the circumferential angle of the reflected light L2 can be in the range of -10 degrees to 10 degrees centered on the Z direction axis.

If the angle D1 is smaller than 70 degrees or larger than 110 degrees, the angle of the reflected light L2 may be outside the range of -10 degrees to 10 degrees around the Z direction axis. This causes a decrease in light efficiency.

In particular, when the angle D1 becomes smaller than 70 degrees, the light reflection threshold angle is exceeded, and thus the irradiation light L1 may be transmitted instead of being reflected by the first pattern line 210.

Meanwhile, a pitch distance between two adjacent first pattern lines 210, that is, a distance P between vertices of each of two adjacent first pattern lines 210 is set to less than 0.5 millimeter (mm). .

The distribution of the first pattern line 210 on the lower plate surface 201 is denser as the distance from the light emitting device 110 increases, and the corresponding distance P may be changed according to the position of the first pattern line 210. However, the distance P is set to become narrower as it moves away from the light emitting element 110 within a range of less than 0.5 mm. As a result, the overall luminance of the display panel 30 can be uniformized.

The reflected light L2 reflected by the first pattern line 210 is emitted from the upper surface 202 at the main angle within the preset range, and is diffused through the diffusion sheet 400 and transmitted to the display panel 30. do.

Hereinafter, an experimental result of comparing the light efficiency by the backlight unit 40 having the configuration according to the present embodiment with the preset comparison target configuration will be described with reference to FIGS. 4A to 4D.

4A to 4D are graphs illustrating an emission angle distribution of light detected on an entire surface of a display panel in a display device to which a backlight unit according to a comparison target configuration is prepared in accordance with the present embodiment.

Here, the structure of the backlight unit according to the configuration to be compared is as follows:

1. The light source unit has the same light emission performance as in the present embodiment;

2. The optical pattern of the light guide plate is a scattering pattern formed by laser or printing,

3. The optical sheet between the light guide plate and the display panel is selectively applied within three sheets of diffusion sheet, prism sheet and protective film.

4A to 4D show distributions of propagation angles of light detected on the entire surface of the display panel in the display device according to the comparison target configuration. That is, each curve of the graph shows how much light is emitted or emitted from the display panel mainly under the conditions, that is, how much is the circumferential angle of the light emitted from the display panel.

The horizontal axis of the graph represents an angle and the vertical axis represents luminance. The angle on the horizontal axis means an angle with respect to the normal axis line with respect to the plate surface of the display panel. As the angle approaches 0, the light efficiency is good. In addition, (+) or (-) of an angle represents a direction.

In this graph, it is important to compare the shapes of the curves, so that the measurement data on which the graph is based is not specified. The above definitions for graphs apply equally to all graphs.

Curves C1 to C4 are shown on the graphs of each of FIGS. 4A-4D.

The configuration conditions of the backlight unit in each curve are shown in Table 1 below.

Light guide plate Diffusion Sheet Prism Sheet Protective film C1 O X X X C2 O O X X C3 O O O X C4 O O O O

That is, the curve C1 is a case where the light exit angle of the light is measured under the condition that only the light guide plate is applied but not all the optical sheets.

Curve C1 shows a circumferential angle of light of 80 degrees, indicating that light efficiency is low. Curve C2 shows a 50 degree circumferential angle of light, and it can be seen that the light efficiency is improved by applying the diffusion sheet as compared to the case of curve C1.

Curve C3 exhibits the highest light emission angle distribution in the region of 0 degrees and 80 degrees, so that the light efficiency is low. On the other hand, the curve C4 under the condition that the protective film is additionally applied, the emission angle distribution of light is remarkable at 0 degrees, the main angle of the light can be seen as 0 degrees.

In the above, the graph of FIGS. 4A to 4D analyzes the outgoing light circumference of the structure to be compared. Hereinafter, the analysis result of the outgoing light circumference angle of the backlight unit 40 according to the present embodiment will be described with reference to FIGS. 5A and 5B. 5A and 5B are graphs showing an emission angle distribution of light detected on the entire surface of the display panel 30 in the display device 1 to which the backlight unit 40 according to the present embodiment is applied.

As shown in FIGS. 5A and 5B, curves C5 and C6 are shown on the graph.

Configuration conditions of the backlight unit 40 in each curve are shown in Table 2 below.

Light guide plate Diffusion Sheet C5 O X C6 O O

Curve C5 may be considered to be excellent in terms of light efficiency because the distribution of the emission angle of light appears most remarkably within a range of -10 degrees to 10 degrees. However, since the emission angle distribution around the zero degree is not symmetrical and shows a deviation, a local deviation may occur in the overall luminance distribution of the display panel 30.

On the other hand, curve C6 under the constituent condition to which the diffusion sheet 400 is additionally applied shows that the main angle of light is 0 degrees, and that the optical efficiency is improved compared to the configuration corresponding to C4 of FIG. 4D, which is a relatively complicated structure. have.

As such, it can be seen that the configuration of the light guide plate 200 and the backlight unit 40 according to the present embodiment is improved in terms of light efficiency while applying a simple structure to the comparison target configuration.

In addition, in the comparison target configuration corresponding to curve C4 of FIG. 4D, the center luminance of the display panel was 5430 nits, the average luminance was 4670 nits, and the uniformity was 82%. Where nits is the luminance unit and 1nits is the luminance of 1 cd per square meter.

In contrast, in the configuration corresponding to curve C6 according to the present exemplary embodiment, the center luminance of the display panel 30 was measured at 5970 nits, the average luminance at 5130 nits, and the uniformity was 82%. Showed an additional optical efficiency improvement of 10% compared to the comparable composition.

As such, according to the present exemplary embodiment, the light efficiency of the light provided to the display panel 30 may be improved.

Hereinafter, the second pattern unit 220 will be described with reference to FIGS. 6 and 7. FIG. 6 is a sectional side view of the main part showing the second pattern part 220, and FIG. 7 is a plan view of the main part showing the traveling pattern of light in the second pattern part 220. As shown in FIG.

As illustrated in FIG. 6, the plurality of second pattern lines 220 are embossed in a lenticular shape on the top surface 202 of the light guide plate 200. Each second pattern line 220 extends parallel to the light irradiation direction from the light emitting element 110, and a cross section cut in the radial direction with respect to the extension direction, that is, a cross section cut along the XZ plane in the drawing It has a shape protruding round from the top surface.

The width W of the cross section of the second pattern line 220 is 100 micrometers (um) or less. The ratio of the height H to the width W of the second pattern line 220, that is, the aspect ratio H / W, is set to 0.35 or more.

It is advantageous in terms of light efficiency when the light emitted to the upper surface 202 is in the range of -10 degrees to 10 degrees about the Z direction axis. However, the light L3 traveling parallel to the Z direction axis, that is, traveling at an angle of 0 degrees with respect to the Z direction axis may not be advantageous in terms of uniformity of luminance of the entire display panel 30 as described above.

Accordingly, the second pattern line 220 may contribute to the above-described luminance uniformity by reflecting the light L3 back toward the lower plate 201.

As illustrated in FIG. 7, the second pattern line 220 may include the first line 220a, the second line 220b, the third line 220c, and the first line 220 that are sequentially arranged in parallel along the −X direction. Four lines 220d and a fifth line 220e are included.

Meanwhile, the light emitting device 110 includes a first light emitting device 111 and a second light emitting device 112 sequentially disposed along the −X direction.

Here, the first line 220a, the second line 220b, and the third line 220c are disposed to correspond to the first light emitting device 111 in position, and the light guide plate 200 is disposed from the first light emitting device 111. ) Is irradiated to the first line 220a, the second line 220b, and the third line 220c. The first line 220a, the second line 220b, and the third line 220c extend along the Y direction, and the light L4 travels in the Y direction along the corresponding lines 220a, 220b, and 220c. And the emission of the light L7 from the lines 220a, 220b, and 220c.

In the same principle, the fourth line 220d and the fifth line 220e correspond to the second light emitting element 112 and guide the irradiation light L5 from the second light emitting element 112.

Here, the third line 220c corresponding to the first light emitting element 111 and the fourth line 220d corresponding to the second light emitting element 112 are disposed adjacent to each other. The third line 220c blocks the irradiation light L5 from the second light emitting element 112 from flowing above the preset level, and the fourth line 220d emits the light from the first light emitting element 111. (L4) can be prevented from flowing more than the predetermined level.

That is, each of the second pattern lines 220 guides the progress and the emission of light emitted from the corresponding light emitting device 110, and at the same time, induces the inflow of light emitted from the light emitting device 110 instead of the corresponding light emitting device 110. Cut off below the set level. Here, since the preset level is a different value depending on the configuration environment of the display apparatus 1, the specific numerical value is not limited.

This makes it possible to implement local dimming on a line or area basis in the display apparatus 1 according to the present embodiment.

Hereinafter, the experimental results supporting this will be described with reference to FIGS. 8 and 9. 8 is a plan view illustrating a guide efficiency test of light by the second pattern unit 220 according to the present embodiment, and FIG. 9 is a graph comparing the guide efficiency result according to the experiment of FIG. 8 with a comparison target configuration.

As shown in FIG. 8, eight light emitting elements 131, 132, 133, 134, 135, 136, 137, and 138 are sequentially disposed along the sidewall of the light guide plate 500 according to the present embodiment. The light guide plate 500 includes a plurality of regions 510, 520, 530, 540, 550, 560, 570, and 580 corresponding to each light emitting device 131, 132, 133, 134, 135, 136, 137, and 138. Each region 510, 520, 530, 540, 550, 560, 570, and 580, although not shown, includes a plurality of second pattern lines 220 extending in the Y direction.

Each of the regions 510, 520, 530, 540, 550, 560, 570, and 580 includes an incident region to which irradiation light from the corresponding light emitting elements 131, 132, 133, 134, 135, 136, 137, and 138 is incident. And a central area that is an area spaced apart from the incident area by a predetermined distance in the Y direction.

In the present experiment, the light emitting device 132 of the second order among the plurality of light emitting devices 131, 132, 133, 134, 135, 136, 137, and 138 is turned on to emit light, and the remaining light emitting devices 131, 133, and 134 are turned on. , 135, 136, 137, and 138 are turned off. In this state, predetermined positions 511, 521, 531, 541, 551, 561, 571, 581 of each incident region, and predetermined positions 512, 522, 532, 542, 552, 562, 572, The luminance of the light emitted from 582 is measured.

For comparison with the present embodiment, the luminance measurement results of the comparison target configuration having the light guide plate not including the second pattern line 220 are shown in Table 3 below.

Nits normalization (%) Light emitting element
No. Light emitting element
condition Incident area Center area Incident area Center area One off 342 417 11 41 2 on 3070 1020 100 100 3 off 276 540 9 53 4 off 88 128 3 13 5 off 30 35 One 3 6 off 12 13 0 One 7 off 8 6 0 One 8 off 4 3 0 0

The unit of measured value is nits, and the unit of normalization value is%.

The positions of the light emitting element number, the incident region and the center region are in the case of FIG. That is, in the case where the light emitting element number is 2, in the drawing, the incident region corresponds to the position 521 and the center region 522. However, the comparison target configuration may have only a difference without the second pattern line 220 compared to the present embodiment. It is only.

The calculation method of normalization is as follows.

In the case of the incident region of light emitting element 1, only light emitting element No. 2 132 is in a state of being irradiated with light, so [(incident region measured value of light emitting element 1) / (incident region measured value of light emitting element 1)] * 100 ( %) That is, about 11% is calculated by [(342/3070) * 100].

In the same principle, in the case of the center area of light emitting element 5, it is calculated as [(center area measured value of light emitting element 5) / (center area measured value of light emitting element 2)] * 100 (%). That is, about 3% is calculated by [(35/1020) * 100].

In Table 3, the results of the normalization of the light emitting device No. 5 135 for contrast comparison are 1% in the incident region and 3% in the central region. The relatively high normalization value in the central region means that the irradiation light from the light emitting device No. 2 132 is diffused and propagated to the area 550 corresponding to the light emitting device No. 5 135.

Meanwhile, the luminance measurement results of the light guide plate 500 including the second pattern line 220 according to the present embodiment are shown in Table 4 below. The calculation method of Table 4 is based on Table 3.

Nits normalization (%) Light emitting element
No. Light emitting element
condition Incident area Center area Incident area Center area One off 420 314 10 25 2 on 4400 1250 100 100 3 off 360 395 8 32 4 off 92 58 2 5 5 off 32 15 One One 6 off 12 5 0 0 7 off 5 2 0 0 8 off 3 2 0 0

In Table 4, as a result of the normalization of the light emitting element No. 5 135 for contrast comparison, it can be seen that 1% in the incident region 551 and 1% in the central region 552 are shown. This means that the light emitted from the light emitting device No. 2 132 is hardly propagated to the region 550 corresponding to the light emitting device No. 5 135 or only a small amount of light is propagated. Even when compared with the case of the comparison target configuration, it can be seen that the normalization value of the central region 552 is improved from 3% to 1% according to the presence or absence of the second pattern line 220.

9 is a graph showing the distribution of normalization values in the central regions of Tables 3 and 4, respectively.

In the graph of FIG. 9, the horizontal axis represents each light emitting device number, and the vertical axis represents a normalization value. Curve C7 represents the central region normalization value according to Table 3 of the comparison target configuration, and curve C8 represents the central region normalization value according to Table 4 in this embodiment.

On the basis of the No. 2 light emitting device 132 to irradiate light, the narrower the width of each curve, the better the guide efficiency or the straightness of the light. Comparing the width W1 of the curve C7 and the width W2 of the curve C8, since W1> W2, it can be seen that the case where the second pattern line 220 is applied as in this embodiment is relatively superior in the linearity of light.

In summary, the second pattern line formed in the predetermined first region of the light guide plate guides the irradiation light from the light emitting element corresponding to the first region to travel and exit along the second pattern line, and from the corresponding light emitting element. Irradiation light propagates to other areas other than the first area, or the inflow of the irradiation light from another light emitting element corresponding to the other area can be blocked to a predetermined level.

Accordingly, according to the present exemplary embodiment, local dimming for each line or region may be easily implemented on the display panel 30.

As described above, the light guide plate 200 of the backlight unit 40 according to the present exemplary embodiment is formed on the lower plate surface 201 so as to extend perpendicularly to the direction of the irradiation light from the light emitting element 110 and to top the irradiation light. A plurality of first pattern lines 210 totally reflecting to the surface 202 and a plurality of second pattern lines 220 extending on the upper surface 202 in parallel to the direction of the irradiation light and guiding the progress and emission of the irradiation light; ).

As a result, the efficiency of the light provided to the display panel 30 can be improved, and local dimming can be easily implemented.

Meanwhile, the embodiment described above may be applied to the display apparatus 900 implemented in various forms. Hereinafter, an example in which the embodiment of the present invention is applied when the display apparatus 900 is implemented as a TV will be described with reference to FIG. 10. 10 is a configuration block diagram of a display device 900 according to the present embodiment. In FIG. 10, the solid line means transmission of an image signal or a control signal, and the dotted line means transmission of light.

As shown in FIG. 10, the display apparatus 900 according to the present exemplary embodiment includes an image receiver 910 for receiving an image signal from the outside, and an image processor 920 for processing the image signal received by the image receiver 910. And a display panel 930 for displaying an image signal processed by the image processor 920 as an image, and a backlight unit 940 for supplying light to display an image on the display panel 930. .

The image receiver 910 receives the image signal / image data by wire or wirelessly and transmits the image signal / image data to the image processor 920, and can be drilled in various ways in accordance with the standard of the received image signal. For example, the image receiver 910 may include a radio frequency (RF) signal, composite / component video, super video, SCART, high definition multimedia interface (HDMI), and DisplayPort. , A video signal according to a unified display interface (UDI) or a wireless HD standard may be received.

The image processor 920 performs various preset image processing processes on the image signal, and outputs the image signal subjected to the process to the display panel 930 so that the image is displayed on the image display surface of the display panel 930. To be displayed. The type of processes performed by the image processor 920 is not limited. For example, decoding, de-interlacing, frame refresh rate conversion, and scaling corresponding to various image formats may be performed. scaling, noise reduction for improving image quality, detail enhancement, and the like.

The image receiver 910 and the image processor 920 may be implemented as an image processing board (not shown) embedded in the display apparatus 900.

Since the configuration of the display panel 930 and the backlight unit 940 is substantially the same as the configuration of the previous embodiment, the description of the configuration of the previous embodiment can be applied, and a detailed description thereof will be omitted.

The above-described embodiments are merely illustrative, and various modifications and equivalents may be made by those skilled in the art. Accordingly, the true scope of protection of the present invention should be determined by the technical idea of the invention described in the following claims.

1: display device
10, 20: cover part
30: display panel
40: backlight unit
100: light source
110: light emitting device
120: module substrate
200: light guide plate
201: bottom plate
202: top surface
203: sidewall
210: first pattern portion
220: second pattern portion
300: reflector
400: diffusion sheet

Claims (12)

In the backlight unit of the display device,
A light source unit disposed in at least one of the corner regions of the display panel;
A light guide plate disposed at a rear side of the display panel and emitting light emitted from the light source to a rear side of the display panel;
The light guide plate,
A first pattern portion having a plurality of first pattern lines extending orthogonally to the direction of the irradiation light on the lower plate surface of the light guide plate, and totally reflecting the irradiation light to the upper plate surface of the light guide plate;
A plurality of second pattern lines extending in parallel to the direction of the irradiation light on the upper surface of the light guide plate, wherein the light propagating in the light guide plate is guided so that the light propagates and exits along the second pattern lines; Backlight unit comprising a pattern portion. The method of claim 1,
And the first pattern line is engraved on the lower plate surface of the light guide plate to have a wedge or prism-shaped cross section. The method of claim 2,
In the cross-section of the first pattern line, the angle of the vertex toward the upper plate surface of the light guide plate is characterized in that the backlight unit is 70 degrees or more and 110 degrees or less. The method of claim 2,
And a pitch distance between two adjacent first pattern lines is less than 0.5 millimeters. The method of claim 1,
And a circumferential angle of light reflected by the first pattern line and emitted from the light guide plate is within a range of -10 degrees to 10 degrees with respect to a normal axis with respect to the rear surface of the display panel. The method of claim 1,
And a distribution of the plurality of first pattern lines on the lower plate surface of the light guide plate is denser as it is farther from the light source unit. The method of claim 1,
And the second pattern line has a lenticular shape embossed on the top surface of the light guide plate. The method of claim 7, wherein
The width of one second pattern line is 100 micrometers or less, and the ratio of the height to the width of the second pattern line is 0.35 or more. The method of claim 1,
The light source unit includes a plurality of light emitting elements sequentially arranged,
The plurality of second pattern lines are disposed corresponding to the plurality of light emitting devices,
Any one of the second pattern lines guides the emission of light irradiated from any one of the corresponding positions among the plurality of light emitting devices. 10. The method of claim 9,
Each of the second pattern lines may block light from being irradiated from the remaining portions other than the one of the corresponding positions among the plurality of light emitting elements to be below a preset level. The method of claim 1,
And a diffusion sheet interposed between the display panel and the upper surface of the light guide plate and scattering light emitted from the upper surface. In the display device,
With display panel
A display apparatus comprising the backlight unit according to any one of claims 1 to 11 for supplying light to the display panel.

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